| 摘要 |
PURPOSE:To prevent the minute retreat phenomenon of an ejection ram from developing during processes excluding ejection process by a method wherein a check valve chamber communicates a first pipe line, which is connected to the oil path side of a four port connection valve, with a second pipe line, which is connected to the oil path of an oil tank side, during a process, in which ejection is stopped. CONSTITUTION:A check valve 11 communicates through a pipe line 8 to a pipe line, which is branched off from a pipe line 23 communicating a four port connection valve 21 with the head side of an ejection ram 22, and through a pipe line 9 to a tank. If the oil, which is the leakage passing from the P port to the A port of the four port connection valve 21, flows from the pipe line 23 into the pipe line 8, said oil flows from the valve gap through the pipe line 9 into the tank, resulting in causing no pressure rise in the pipe line 23 due to the leakage oil even after a long time. This is to allow to prevent such bad effect that the ejection ram gradually advances from its retreat position for ejection during processes excluding ejection process from developing. Since the quantity of oil flowing through the pipe line 23 into the pipe line 8 is large during the advance or retreat of the ejection ram, a steel ball 3 is pressed against a sealing surface 10 so as to check the pipe line 8 completely. |
